Electrical conductor



Dec. 3, 1935. A. o. AUSTIN 2,022,339

ELECTRICAL CONDUCTOR Filed Dec. 27, 1932 Fig.4 F296. 1 9.6.

Fig/K Fig/6 INVENTOR f v 4 Arf/wrO. Aus fin Y ATTORQZ Patented Dec. 3,1935 PATENT I OFFICE z,o2z,sz9 v ELECTRICAL coNnUc'roa Arthur 0. Austin,near Barber-ton, Ohio, assignor,

by mesne assignments, to The Ohio Brass Company, Mansfield, Ohi Jersey0, a corporation oi New Application December 27, 1932, Serial No.648,850

5 Claims.

This invention relates to conductors for electricity and particularly tohigh voltage conductors, especially for heavy loads.

One object of the invention is to provide a con- I 5 ductor cable whichwill operate at high voltage without the production of corona discharge.

A further object is to provide a conductor which will have the necessaryflexibility, even for large diameters'and one in which the amount ofcon-- 10 ducting material will be small for a given diameter andstrength of conductor.

A further object of the invention is to provide a conductor which willtend to throw of! drip water to provide a high corona point for wetconlli ditions.

A further object of the invention is to provide a cable which will notbe easily damaged by vibration and which will tend to absorb energy ofvibration, thereby holding the amplitude 01 vibration within safelimits.

A further object of the invention is to provide a conductor having ahigh-strength core, a flexible spacer and an outer sheath of highconducting material.

Other objects and advantages will appear from the following description.

The invention is exemplified by the combination and arrangement of partsshown in the accompanying drawing and described in the follow-,

ing specification, and it is more particularly pointed out in theappended claims.

In the drawing:

Fig. 1 is a fragmentary elevation of a portion of a conductor showingone embodiment of the 36 present invention.

Fig. 2 is a transverse section of the conductor shown in Fig. 1.

Figs. 3, 4, 5, 6, 7, 8, and 9 are sections of various forms of .spacermembers which may be used 40 as a part of tlie invention.

Figs. 10, 11, 12, 13, 14, 15, 16, 1'7, and 18 are fragmentary sectionsof various forms of outer conducting strands or segments which may beused in the present invention, Fig. 15 including also a cross section ofthe inner portion of the conductor.

Fig. 19 is a fragmentary elevation of a portion of the form of conductorshown in Fig. 15.

The amount of power which can be transmitted to over a high voltageconductor of a given size, with a given percentage of loss in theconductor, increases approximately as the square of the voltage.Therefore, it is very important that a high voltage be used where it isdesired to reduce the as cost per 1:. w. or k. v. a. transmitted. How--(01. rza-rs) ever, the voltage is generally limited by the loss due tocorona or brush discharge from the conductor, or due to radiointerference caused by discharge from the conductor.

Where very large blocks of power are involved, 5

section of the copper, aluminum or other com I ducting material used inmaking up the conductor. If the voltage is sufllciently high, it is alsopossible to use higher strength materials even 16 though they havepoorer conductivity.

' In my prior Patent #1,626,776, I have shown means for increasing thediameter of the conductor and also its mechanical strength. In Patent#1526377 I have shown a coating of insulating 20 paint or varnish forpart or all of the outer members of the conductor so as to raise thevoltage at which corona will start. In the present invention, furtherimprovements have been made to provide conductors of better economicpossibili- 26 ties. In this improved conductor, particular attention hasbeen given to the provision of a conductor which may be easilyfabricated and in which the amount of eflective conducting-material maybe reduced without affecting the mechanical reliability or desiredelectrical properties. 1

In the form of the invention shown in Figs. 1 and 2, the conductor isformed with an outer conducting layer composed of strands or segments M.The inner or high strength core II is made of galvanized steel or othersuitable material. In order to prevent collapse or disarrangement of theouter strands, a spacer member I 2 is placed tail later.

In Fig. 1 the outer layer is made up of sectors it which have radialabutting edges. The outer contour of each sector II has a smallerradius. than that of the conductor taken as a whole. This causes theouter surface of each sector to project it further at its'center than atthe corners of the sector. This arrangement has certain very materialadvantages in reducing corona loss and in throwing off drip water. Owingto the fact that the center of the segment projects beyond the edges,the lines of force will be greater at the center points of the segmentsthan they would be if the centers of the segments did not pro-v jectbeyond the edges, as in the case where the outer segment surfaces form acontinuous circle. The abrupt outer comers at the edges of the segmentswill tend to start corona. or brush discharge. The center of the segmentmay be made very smooth and since it may be given a much larger radiusof curvature than the corners,

the corona point can be greatly raised for a conductor made up in thisway. The contour of the outer surfaces of .the segments will depend uponthe amount of screening desired, the width of the segments, the diameterof the conductor, and

' the effective concentration of stress or lines of force at the edgesof the segments.

The individual segments may be made in a variety of forms for locking inplace or to obtain greater flexibility or for other reasons. However, ingeneral where the highest corona voltage is desired, it will beadvisable to have the center portion of the' segment project beyond theedges so as to eflectively screen the latter. This arrangement also hasthe advantage that drip water which tends to cause streamers from theconductorwill be more readily thrown off. If the conductor is coatedwith an insulating paint, varnish or enamel, as shown in my prior Patent#1526377, the projection may be greater than where it is uncoated. Theprojecting surfaces will greatly facilitate the coating of the conductoras the amount of material required for coating the projecting portionsonly will be considerably less I than where'the entire surface iscoated.

- While various forms of spacers may be used between the high strengthcore H and the conducting layer or segment III, as shown in my priorPatent -#1,626,'176, an improved type of spacer I2 is shown in Figs. 1and 2 which has a particular advantage where the outer diameter of theconductor is large compared to the cross section of conducting material.With this class of conductors, it is desirable to increase, as much asprac- "tical, the space between the high strength core H and the outerconducting layer made up of segments 10. While one of the'iorms ofspacers shown in my prior patent may be used, a more flexible spacer andone of improved mechanical strength has been used for the largerdiameters of conductor.

Spacer i2 is shown in detail in Fig. 3. In this figure an inner coremember i3 is made 01 the same material as the outer elements [4 and L5,or

50 the core member l3 may be made of steel or other material if desired.The outer layer of the spacer is made of two helically wound members I4and I5. These preferably are of zinc or other material which willprotect the core and outer layer from possible damage due toelectrolytic action. The members it and ii are simply wrapped around thecenter member, some slight space being allowed if desired between theedges of the outer members. The two members l4 and 45 therefore are inthe form of helical members,

the core member 13 preventing them from collapsing under pressure andhelping to hold them in position relative to each other. A spacer madeup in this manner may be readily wrapped around the high strength coreduring the iabrication'ot the conductor. Even though the members II andI5 are of relatively brittle material, their flexibility and the use ofthe core l3 will make it possible to give the spacer members IIIpractically any pitch or lay desired. 5

A somewhat simple form of spacer is shown in Fig. 4 in which thesegments l6 and fl are prevented from slipping by the core member [8.The two members It and I! are twisted about the axis of l8 so as toprovide flexibility when the 10 spacer member I2 is wrapped around thecore. The core member l8 acts as a key in preventing the two segments l6and I! from sliding past I each'other. The core member l8 may be of thesame material as the segments l6 and H or may 15 be galvanized steel, orany other suitable material depending upon the result desired. In somecases the key member l8 may be omitted. However, in this case, the-pitchfor the outer members l6 and I1 will have to be changed to give 20 agreater number of turns per given length of spacer than where the coreI8 is used.

Of course, it is possible to use any desired num-. ber of segments informing the spacer strand. However, it should be capable of transmitting25 considerable force or pressure between the outer layer and the innercore. This makes it possible to develop a tension inthe inner member sothat-the full mechanical strength of the inner core can be utilized. Thepressure between the 30- outer and inner layer transmitted through the.spacer strand will depend to a considerable extent upon the tension inthe conductor. This tends to bind the several component parts togetherso that all members act as a unit inechani-1 351 cally. Since the cablesare very long, it is not necessary to transmit very high pressures atanyone point, as accumulative benefit may be obtained. Even should theentire conductor or some of the conductor strands be broken, due to 40excessive mechanical load or burning from a power are or other cause,the friction between the several component parts or the conductor willcause all 01' the members to act as a unit at a comparatively shortdistance from the break, if 45 the construction has been carried out asabove described.-

Fig. 5 shows a spacer member made up in two parts I! and 20 such thatthe segments interlock. This interlocking and the twisting of the 5segments will give them the necessary flexibility and mechanicalstrength, and at the same time develop suflicient mechanical strengthfor any pressure between the outer and inner members.-

Fig. 6 shows a member similar to that of Fig. 3. 55

except that the core 2i is surrounded by a single ribbon or wrapping 22.

Fig. 7 shows a spacer member 23 made up in the form of a helix without acore. A member made up in this way can be given any degree of e0flexibility and the resiliency provided may be beneficial in someconductors. The helix may be made of a ribbon, or round or square wire.

If desired the construction in Fig. '7 can be modified to that shown inFig. 8 in which a member 24 is wound in rectangular or square contour toprovide increased bearing area. Other forms may be used which wouldincrease the flexibility notonly of the spacer member but of the entirecable. A simple cylindrical wire 25, as shown in Fig. 9, may also beused-fer a spacer where the required amount of spacing is not too great.

' A number of diflerent forms of conductorstrands may be used for theouter segments in aoaasse addition to those'shownat It 'in Figs. 1 and2. Fig. 10 shows a locking type of segment 26 which can be used where itis desired to screen-discharge from the abutting edges as previouslyexplained. The tongue 21 on one edge of each segment meshes with agroove 28 on an adjacent segment.

Fig. 11 shows another form of conductor se ment in which alternatestrands 29 are made larger than the intervening strands 30. Adjacentstrands are interlocked so as to prevent displacement by bending of thecable.

Fig. 12 shows another form of interlocking segment iii in which eachsegment is provided with a tongue 32 at one corner engaging a groove inthe adjacent segment.

Fig. 13 shows the conducting layer made up of outer'members 33 and innersegments 34. This type of construction makes it possible to increase theflexibility of the conductor materially. The construction also has theadvantage that the lay or twist may be in one direction for the members34 of the inner layer, and the other direction for the members 33 of theouter layer. This tends to reduce the reaetance of the conductor,particularly where the pitch of the outer members is small in order toobtain flexibility. Any movement such as that due to vibration will tendto cause the inner and outer layers to slide upon each other.' Thefriction between these inner outer segments, the flexibility of theconductor generally will be materially increased. However, it isdifllcult to provide uniform spacing or clearance unless some definitemeans is used for securing this spacing. One method is shown in Figs. 15and 19 in which a very small burr or rib I is placed on the edge of themain segment 36. This member 35 may be continuous or may be in the formor small projections. Owing to the very small section of the member 35,any abnormal pressure will cause the small member to be seated in theadjacent segment or simply to compress. This method provides auniformly'distributed spacing but at the same time permits movementbetween adjacent segments necessary to increase the flexibility oi. theconductor. This spacing also permits of moisture running out of theconductor, so that accumulation at a low point will not be possible.

Another way to provide slight spacing while permitting lateral movementis to bend the segments edgewise. If this is done, the bends in adjacentsegments should be offset with respect to each other during thefabrication of the conductor, or bent segments may be alternated withunbent segments. This arrangement may be used with any of the segmentshaving radial edges or those having locking means. The number and sizeof thesegments of course can be varied, depending upon the resultsdesired in the cable.

The high strength core makes it possible to reduce the required heightof the supporting structures for a given ground clearance at the centerof the span. It also makes it possible to use considerably longer spansand reduce the number of structures if desired. 'Ihegreatly increasedstrength of the conductor due to the high strength core makes itpossible to provide greater effective rigidity in the conductor, due tothe increased tension, so that bending of the con- 5 ductor, due to windor other conditions, will be less so that greater rigidity in thesegments and the outer layer may be used without causing trouble due tobending or flexing. This is evident from the fact that high tensions inthe conductor tend to cause it to act'as .a rigid member.

Steel is one of the most desirable metals for resisting vibration. Theuse of a high strength steel core, therefore, tends to increase themechanical reliability of the conductor very materially. In addition,the strength of the core may be several times that of the conductingmaterial so that practically all the mechanical load may be carried bythe core if desired, permittingof a very thin outer wall. 20'

In general, the lower cost of material used for the spacer makes itpossible to produce a conductor of large diameter and high corona point,and of good mechanical properties at a low cost.

This makes it possible to use considerably higher 1 transmittingvoltages even where the blocks of power are not very large, as thesection of conducting material may be made small without mechanicaldifiiculties. With the construction shown, the thickness of the outerconducting layer may be considerably less, without danger of collapse,than where a simple hollow conductor Fig. 16 is somewhat similar to Fig.10 except that in place of ribs 21 of Fig. 10, the segments 31 35 areprovided with V ribs and notches at their engaging edges. I

Fig. 1'7 shows a difierent form of conductor strands or segments whichmay be used with or without an internal core and spacer. In this form ofthe invention, each segment preferably has a bulging face 40 whichprojects far enough to prevent discharge from the rounded corners at lland 42'. In a conductor it is quite important that the strands orsegments do not become 46 displaced with respect to each other'duringconstruction or under operating conditions, and it is also important,particularly where an internal supporting structure is not used, thatthe mem-- bers have enough mechanical strength so that the 50 conductorcan be clamped at suspension or dead end points. It is highly desirablethat the strands oi the conductor do not slip by each other undertangential forces produced by the weight of the conductor or by grippingmeans used in clamping.

In the construction shown in Fig. 1'7, the segments are provided withtongues 43. These tongues may be of uniform section or tapered tofacilitate drawing or forming. In order to prevent the strands fromslipping past each other, two means-may be employed to advantage. In onearrangement the tangential force on the abutting surfaces tends to causea slight interlock. This force will increase with the tension on theconductor and as the pitch becomes less or the number of twists becomegreater for a given length of conductor. One edge of each segment isprovided with a slight groove 44 and the other edge with a matchingprojection or rib 45. It is important that when the two adjacentsegments are forced together by tangential stress, they will tend tolock and not become displaced. In order to increase the reliability, theproject-' ing tongue 43 may be extended well under the adjacent segment.If in fabrication of the conductor the lay of the strands is such thatthere is a tendency for the tongue 43 to move outwardly and for theopposite edge 45 to move inward, the strands will tend to holdthemselves together very flrmly. This arrangement can be used eventhough there is no recess 44. By giving the members a torsional twistwhich may come about naturally in the fabrication or may be emphasizedif desired, a conductor will be formed in which it will be verydiilicult to, dislodge the adjacent sections. Of course it is notnecessary that the segments be smooth on the inside, and the tongues 43may be of any desired thickness or any desired length. However, if thesetongues are long it will be exceedingly diflicult to dislodge thestrands, and if for any cause a strand is dislodged, it will be possibleto put it back into position.

This arrangement of segments or strands makes it possible to provide afairly definite pressure between the tongue 43 and the segment above,-regardless of the tangential pressure. This will be a very greatadvantage in some cases where it is desired to dampen out vibration. Itis evident that where the friction is too great between the segments,they will act as a unit. However, if the pressure can be reduced to thepoint so that vibration will cause slipping, energy will be absorbed andserious vibration will be prevented. Therefore, it is seen that bycontrolling the pitch of the conductor and the torsional stress in thestrand, practically any degree of pressure between the parts may beprovided. Owing to the large areas which may be provided between thesurfaces, there will be little danger of seizing between the strands, sothat a frictional or bearing member will not be necessary although thisof course may be provided. Such a bearing member is shown at 46 in Fig.18, which figure is otherwise like Fig. 1'7. The hearing surfaces ofcourse can be coated with any lubricant or material which will protectthe wearing surface or control the coefilcient of friction.

Any tendency for burrs to form in the manufacture of the cable may betaken care of by using a drawing die having the exact contour desiredfor the outside of the segments. The die will smooth up any roughness asthe cable is drawn through- If additional force is needed and aninternal core is not used, a drawing mandrel or die may be used insidethe cable to inaoaasse crease the force between the segments and theoutside die.

I claim:

1. A conductor comprising a tubular shell formed of flattened strips ofconducting material 5 placed edge to edge, the edges of said stripsbeing 3 disposed substantially radially of said conductor, one edge ofeach strip having a rib thereon spaced from the outer and innerextremities of said edge and engaging the edge of the adjacent strip,ad- 10 jacent edges 01' said strips being spaced apart by said ribs.

2. A conductor comprising a shell of helically wound flattened strips ofconducting material placed edge to edge, the edges of said strips being15 disposed substantially radially of said conductor, one edge of eachstrip having a rib thereon spaced from the outer and inner extremitiesof said edge and engaging the edge of the adjacent strip, adjacent edgesof said strips being spaced apart by go said ribs.

3. A conductor comprising a core member, an outer shell of conductingmaterial-and a spacer helically wound upon said core member between saidcore member and said conducting shell, said 25 spacer comprising aplurality of ribbon shaped strips bent into arcuate form in crosssection and helically twisted together.

4. A conductor comprising a central core memher, a spacer helicallywound upon said core member and a conducting shell disposed outside ofsaid spacer, said spacer comprising a core member, and a ribbon memberdisposed upon the surface of said core member and wound helicallythereon.

5. A conductor comprising a high strength core member, a spacer woundhelically upon said core member and a conducting shell disposed aboutsaid spacer, said spacer comprising a plurality of strands woundhelically together about its own axis to provide flexibility, saidconducting shell comprising a plurality of flattened strips ofconducting material disposed edge to edge about the periphery of saidspacer, theouter surface of each of said strips being bowed outwardly 45I

